Improvement in electrotype-dies or molds for molding plastic materials



aura saw DAVID SORYMGEOUR, OF FOXBOROUGH, MASSACHUSETTS.

Letters Patent No. 111,688, dated February 7, 1871.

IMPROVEMENT m ELECTROTYPE-DIES OR MOLDS FOR MOLDING PLASTIC MATERIALS.

The Schedule referred to in these Letters Patent and making part of thesame.

To all to whom these presents shall come.-

Be it known that I, DAvID- SonYMeEoUR, of Foxborough, in the county ofNorfolk and State of bias sachusetts, have made an invention of a newand useful Mode of- Obtaining Electrotypc-Dies or Molds for producingarticles of ornament or use from animal or vegetable pulp; and do herebydeclare the following,

for a patent for which has. been recently allowed by tbe United'StatesPatent Ollie-e.

In order to carry out this invention of Curtiss it becomes necessary toprocure a matrix which shall conform, in the most minute details, to theobject of utility or art which it is intended to reproduce in largenumbers, at low cost, from paper pnlp; and

;-1\I y invention is intended to produce in an economiealmanner a moldor matrix forthis purpose; and to this end I proceed substantially asfollows:

First, I procure or fashion a model of a certain object of an artisticor useful nature, whether a pictureframe, an ornament forjfinefurniture, a molding, or any of the thousand-abd-one subjepts which comewithin the scope of the useful arts, suchmodel or design being fashionedin wood, wax, gutta-percha, plaster of Paris','composition,- or anymaterial or substance which may be worked to the best advantage;

Having acquired a suitable model, I apply a film of wax to the blank orobverse side thereof, in order to obtain a convenient and inexpensivemeans of attaching it toa case or'form of copper, this case or formserving to insure the correct position of the model in the electricbath-in which it is immersed.

The case or form last named is produced from sheet.- oopp er, and of ageneral outline to conform to the .principal curvatures or boundaries ofthe model, and,

when completed, is entirely incased in a thin jacket of wax. I nowattach the model to this copper form by heating and fusing the wax uponthe latter, and applying theb'ase or back of the model to it, to whichit will firmly adhere when the wax solidifies.

Having thus prepared and united the model and copper base, a suitablevarnish is prepared by dissolving wax in naphtha, and a thin coat ofsuch varnish is-applied with a soft brush to the exterior or ornamentalface or portions of the model which-are not covered by wax, the natureof this varnish causing it to dry in a short time, while its consistencyis or should be such that the lines, or irregularities, or traccry ofthe model, no matter how minute or finely out, shall retain theirprimitive condition.

In pursuance of the objects of the invention, 1 next an equivalentsubstance, which will adhere thereto in sufficient quantity to cover allits irregularities or sin nosities, a certain degree of rubbing with abrush or other soft object being applied to produce a polished surface,the purpose of this dress of plumbago being in part to prevent adhesionof the copper deposit to the model, but mainly as a nictallic vehiclewhereby the copper in the bath is induced to creep on and over themodel.

A-ledge or inclosing-wall of wax should nowbe applied to the edge of thecopper form or base, in order to prevent waste of copper in theelectrotyping process to which it is subjected, and the whole immersedin the bath of an electric battery, the suitable connections being made,by which means a thin deposit of copper is, in a given time, laid uponthe'glazed surface of the model, the plumbagointervening.

\Vhen the copper has acquired therequisite degree of thickness, whichwill ordinarily result in from three to five days, thewhole is'to'be.removed from the bath and plunged in hot water, by which means thewaxconnection between the model and the copper form is sundcred, and thetwo separated, the wax being in the act entirely cleaned from oil both.

At this stage of procedure I remove the model from the copper shellwhich surrounds it, this removal of the model being elfected in variousways, according to the nature of the material of which it i's'composedifof wax, gutta-percha, or .other easily fusible substance, by melting; ifof plaster of Paris, 8w, by breaking-thus leaving a thin and delicatenegative mold or matrix of copper, which is a perfect fac stm-ilc of theoriginal model, even to the most minute details.

I next apply to the interior or ornamental face of! the matrix a glazingof any suitable substance,- which shall protect it from the accidentaladhesion of tin, of which a thin film is to be applied to the obverse orback side of the matrix by the ordinary elcctrotyping process, this filmof tin being the medium whereby to subsequently solder the matrix toasuitable base or means of support.

Continuing this operation, I now procure a suitable vessel or flask ofcast-iron, of such extent as to easily contain the mold, the interior ofthis flask being of a size and form to produce a plunger or tenon from amolten metal poured within it, which shall fit the. socket of thehydraulic press, in which pressure is applied to the contents of themold, a filling-orifice being made in the bottom of theilask, throughwhich the molten metal is poured, as hereinafter explained.

At this stage, after procuring a flask, as above stated, I'obtain ablock or mass of wood, or a suitable soft and easily-carved ormanipulated material, the outline of this block in horizontal sectionbeing equal to the horizontal area of the interior of the flask which itfills. I next carve or impress on the upper surface of this block acavity or depression of a form and depth corresponding to the exterim orobverse side of the copper mold, such mold being deposited in thiscavity while the block rests upon the bottom of the flask, it beingobserved that the space intervening between the outer boundary of themold and the inner wall of the flask is of a depth equal to thethickness of the wall of the metallic backing which we are ,now about towhich leaves the flask, with its contents, resting upon said plate. Inow remove the flask, leaving the contents standing upon the plate, theblock or support being uppermost, after which I remove the block careefully from ed the copper matrix, which latter remains adhering to andresting upon the sand core, which has taken the impress of the matrix.From this point the completionof the operation is simpleaud easilyunderstood: the flask, bottom up, is returned to place ever and aboutthe sand core and matrix, and firmly bolted to the plate upon which thelatter rests, and a quantity of molten metal poured into the flaskthrough the orifice in its bottom, such metal filling the flask 'and thespace between its inner periphery and the oxterior wall of the matrixwhich the removal of the block or core-box created. The metal, havingbecome cool, is removed from the flask, the sand, core cleaned fromthematrix, and thelatter, with such metal backing adhering-to it, beingin a state ready for use.

The pedestal or body of metal deposited about the exterior of the mold,as above stated, constitutes a solid and durable support or backing tothe same, without which the 1nold,.owing to its frail character, couldnot be successfully used.

The base of this backing orpedesial is, as before stated, of a size andform to fit the socket of the press in which the mold 'isnsed. v

Any suitable substance. such as pulp from animal and vegetable fiber,forced into the matrix by hydraulic or other pressure will assume theidenticalform and impress of the same.-

I am aware of the existence of certain improvements in clectrotype-diesfor making imitation-straw States -'No. 61,074,'in which is described aprocess somewhat analogous'in principle, but totally different in detailfrom mine..'- In this patented process a flat plate of copper wasemployed, upon which the model in straw was secured ;-'and, if thismodel was of a curved or irregularexterior, as, for instauce,.the rim ofa hat, a small. portion only of such exterior would touch the place,generally, at but two isolated points. As the copper depositcd'by theelectric battery-upon the exterior of the mold can creep upon the sameonly at these twopoints, the process of depositing a copper shell of therequisite thickness was a matter of considerable time. I

By the employment of a copper base, of a form to adapt itself to thecurves or irregularities of the outline of some principal part of themodel, I obtain a union of two large surfaces, bywhich the deposition ofthe copper upon the model is greatly hastened.

By'the employment of the flask and core-box I obtain a very greatadvantage over the "above-named patented process in producing the sandcore or support for the matrix hereinbei'ore alluded to, since I amenabled to mold the shoulder of this core directly in consonancewitltthe outline of the principal side of the model, which, in the caseof a straw hat, is the under side of the rim, while in the patentedprocess above named the requisite amount of metal is removed by thelabor and expense of chipping and reducing with a chisel.

Claim.

1 cla1m- The mode herein described of producing a matrix or mold, andalso-a support or backing for the same.

' DAVID SGRYMGEOUR.

goods, as shown in Letters Patent of the United.

